FT
If the Big IF was good news, it is presently very doubtful whether you will get a Sim check the following day due to the Sim being booked out til April-ish already. Probably something to do with pilot requirement at the mo, you've probably seen the recruitment figures for LH /SH in previous threads.
In addition to this has anybody tried to reschedule their selection date outside the dates mentioned on their website?
Not sure what you mean. Rescheduling is a consideration for any application if your plan changes, but you can only book the dates they publish. On my selection day only 7 out of 12 turned up, one person canceled that morning! It might even be worth contacting the HR dept at the last minute for any late slots, should you be in the UK.
Obvious Top-Tip- get a good nights rest before the day. The selection day is long, arduous and demands your ultimate concentration. You will kick yourself if you rock up, eyes bleeding and then fail. You can't reapply for 11 months...apparently.
Good luck.
SC